This invention relates to a steerable beamformer for a sonar system and more particularly to a steerable beamformer which utilizes solid state components to form and steer the sonar beam so that tracking of a sonic emitter may be achieved without any mechanically moving components.
The preferred embodiment of the invention will be described as a replacement for a tracking sonar which uses a mechanical scanning element to make selective contact with the acoustic transducers substantially uniformly distributed over a spherical surface. The spherical surface typically has greater than 1200 transducers of which the mechanical scanner makes contact with greater than 200 elements. The desire for making a smooth transition between the electrical contacts of adjacent transducers while avoiding transients produced by the switching from one transducer to another within the mechanical scanner makes it necessary to utilize complex brush arrangements with small mechanical tolerances thereby resulting in great expense for the fabrication of such a mechanical scanning device. In addition, the mechanical scanner requires considerable volume which in some sonar applications is at a premium and could be better utilized, as in this invention, by providing a space for the electronic components of the sonar system. Finally, the mechanical scanner requires highly skilled maintenance personnel and repairs can only be made at base facilities specially equipped for this purpose.
It is therefore an object of the present invention to provide a solid state tracking system instead of a mechanical scanner. It is a further object of the invention to provide a tracker which has smooth and accurate beam steering with the absence of transients produced by the transfer to adjacent transducers during the process of moving the tracking beam.
It is a further object of the invention to maintain accurate depression/elevation steering at angles where the mechanical scanner starts to lose contact with transducers because of the truncation of the transducers on the sphere at large depression or elevation angles. It is a further feature of the invention that a relatively small volume and low power are required relative to the mechanical scanner.
Another major feature is the absence of special maintenance requirements since repair is done at the electronic module level which requires electronic technician skills readily available onboard ships.